1. Field of the Invention
The present invention relates to a traction type elevator having a cage suspended by cables placed around car sheaves.
2. Description of the Background
FIG. 1 is a front view of one example of a traction type elevator, and FIG. 2 is a perspective view of an elevator cage shown in FIG. 1.
In FIG. 1 and FIG. 2, opposite ends of a cable 82 are secured to the upper part of a shaft 83. The cable 82 is placed around a traction sheave 85 driven by a hoisting machine 84 having a motor (not shown). A cage 80 for accommodating passengers and a counter weight 86 for balancing the cage 80 are suspended by the cable 82 through a weight sheave 87 and car sheaves 81 of the cage 80.
In this type of elevator, the cable 82 and the traction sheave 85 are located within the space between the cage 80 and a shaft wall 88. Therefore, if the hoisting machine 84 driving the traction sheave 85 is located within the space between the cage 80 and the shaft wall 88, the cage 80 can move up and down without expanding the size of the shaft 83.
In general, when the cage 80 stops at a floor in order to let passengers on and off the cage 80, the traction sheave 85 is locked by a brake (not shown) so as not to rotate. After passengers get on and off, at the time the cage 80 starts to move, the brake is off. The weight of the counter weight 86 is designed approximately half of the maximum permissible load of the cage 80. That is, if the maximum permissible load of the cage 80 is 1,000 lbs, the weight of the counter weight 86 is 500 tbs. When passengers weighing a half of the maximum permissible load board the cage 80, the cage 80 and the counter weight 86 are nearly balanced. Accordingly, if the upward bound cage 80 is filled with passengers at a floor, at the moment the brake is turned off in order to move the cage 80 upwardly, the cage 80 moves downwardly for a moment and then moves up as requested. On the contrary, if the downward bound cage 80 has no passengers at a floor, at the moment the brake is turned off in order to move the cage 80, the cage 80 moves upwardly for a moment and then moves down in the right direction. To prevent the above unexpected sudden movement of the cage 80, the motor of the traction sheave 85 is provided with a necessary torque according to a load of the cage 80 before the brake is turned off. The load of the cage 80 is detected by a load sensor. In conventional elevators, the cage has a xe2x80x9cdoublexe2x80x9d type construction in which the cage is composed of a cab for accommodating passengers and an outer frame supporting the cab through a rubber elastic member (see JP 10-119495), and the load detector is installed between the cab and the cage frame in order to detect the deformation of the rubber elastic member. Then the load of the cage 80 is calculated on the basis of the deformation of the rubber elastic member.
However, in the above mentioned elevator, since the car sheaves 81 near the cage 80 rotate fast in contact with the cable 82, vibration and noise can be transferred to the cage 80 easily.
Further, vibration caused by a tension change of the cable 82 around the hoisting machine 84 can be transferred to the cage 80 via the car sheaves 81.
To attenuate vibration and noise in the conventional elevator cage having the xe2x80x9cdoublexe2x80x9d construction as mentioned above, and elastic rubber members are installed between the cab and the cage frame. But this makes the cage 80 heavier and complicates the structure of the cage 80.
Accordingly, one object of the invention is to provide an elevator suspended by a cable through car sheaves, which can improve comfort of a ride in the cage without using the xe2x80x9cdoublexe2x80x9d construction in which the cage is surrounded and supported by an exterior frame.
This and other objects are achieved according to the present invention by providing a new and improved elevator including a cage configured to move up and down in a shaft along a guide rail, a plurality of car sheaves installed at a bottom of the cage, a cable placed around the car sheaves and configured to suspend the cage, a hoisting machine having a traction sheave configured to drive the cable, a base extending in a width direction of the cage and configured to support the car sheaves, and a first elastic member lying between the cage and the base.